Miniature spindle potentiometers and method for producing such potentiometers

ABSTRACT

A miniature spindle potentiometer for disturbance-free operation adjacent and generally parallel to adjacent similar potentiometers has a small-area profile of narrow width approaching the profile and width of its spindle. It is composed of simple components which may be rapidly assembled into complete potentiometers. The potentiometer has a special slotted nut having two nut sections of strong elastic and insulating polymer material which are biased into play-free threaded engagement with a rotatable spindle which moves the nut and a contact spring coupled thereto along the spindle. Elongated resistance and contact tracks extending generally parallel to the spindle and transversely to the potentiometer mounting surface are slidingly engaged by the moving contact spring. The elastic material of the slotted nut causes the nut and spindle threads to glide across and over their engaged threads without damage and wear of the nut threads, even while the nut remains stationary in an end position while the spindle continues to rotate at substantial speed. A Ushaped contact spring has two contact arms which contact the parallel resistance and contact tracks, respectively, and its sheet junction section is coupled to the moving nut by interfitting coupling projections and recesses. Thus, the nut has at least one pin projection which enters into a corresponding recess or opening in the sheet junction section of the U-shaped contact spring. All components are of simple shape which make possible their rapid production and assembly on a mass production basis into completed potentiometers. The slotted nut of elastic material enables assembly of all potentiometer components except the spindle within a plastic polymer housing. The threaded spindle is thereafter inserted into the housing and into threaded engagement with the inwardly biased threads of the slot-separated nut sections. The exterior end of the spindle which passes through a passage in a transverse housing wall is surrounded by a housing extension which forms with this exterior spindle end a labyrinthine packing which suppresses entry of dust and other contaminants into the housing interior.

United States Patent [72] Inventors Fritz Jestrzemslti;

Dieter Korbus; Gerhard Schulze, all of Berlin, Germany 21 Appl. No.28,803 [22] Filed Apr. 15, I970 [45] Patented Jan. I], 1972 [73]Assignee Steam-Magnesia Aktiengesellschatt Laul a.d. Pegnitz, Germany[32] Priority May 24, 1969 [33] Germany [31 G 69 2] 039 [54] MINIATURESPINDLE POTENTIOMETERS AND METHOD FOR PRODUCING SUCH POTENTIOMETERS 7Claims, 16 Drawing Figs. [52] U.S. Cl... 338/180, 338/183, 29/610 [51]lnt.Cl 1101c 9/02 [50] Field of Search 338/176, 177, 178, 179, 180, 181,182, 183; 29/610 [56] References Cited UNITED STATES PATENTS 2,958,06210/1960 Barden et al.. 338/180 3,412,362 11/1968 Woods etal..... 338/1833,371,305 2/1968 DeLong et al. 338/183 X 3,400,355 9/1968 Van Benthuysen338/183 2,777,926 1/1957 Bourns 338/183 X 2,976,507 3/1961 DiGirolamo etal 338/183 X 3,017,565 1/1962 Carson et a1 338/176X Primary Examiner-Lewis H. Myers Assistant Examiner-D. A. Tone Attorney0strolenk, Faber,Gerb & Soffen ABSTRACT: A miniature spindle potentiometer fordisturbance-free operation adjacent and generally parallel to adjacentsimilar potentiomcters has a small-area profile of narrow widthapproaching the profile and width of its spindle. It is composed ofsimple components which may be rapidly assembled into completepotentiometers. The potentiometer has a special slotted nut having twonut sections of strong elastic and insulating polymer material which arebiased into playfree threaded engagement with a rotatable spindle whichmoves the nut and a contact spring coupled thereto along the spindle.Elongated resistance and contact tracks extending generally parallel tothe spindle and transversely to the potentiometer mounting surface areslidingly engaged by the moving contact spring. The elastic material ofthe slotted nut causes the nut and spindle threads to glide across andover their engaged threads without damage and wear of the nut threads,even while the nut remains stationary in an end position while thespindle continues to rotate at substantial speed. A U-shaped contactspring has two contact arms which contact the parallel resistance andcontact tracks, respectively, and its sheet junction section is coupledto the moving nut by interfitting coupling projections and recesses.Thus, the nut has at least one pin projection which enters into acorresponding recess or opening in the sheet junction section of the U-shaped contact spring. All components are of simple shape which makepossible their rapid production and assembly on a mass production basisinto completed potentiometers. The slotted nut of elastic materialenables assembly of all potentiometer components except the spindlewithin a plastic polymer housing. The threaded spindle is thereafterinserted into the housing and into threaded engagement with the inwardlybiased threads of the slot-separated nut sections. The exterior end ofthe spindle which passes through a passage in a transverse housing wallis surrounded by a housing extension which forms with this exteriorspindle end a labyrinthine packing which suppresses entry of dust andother contaminants into the housinginterior.

[J g HI PATENTEI] JAN] 1 1972 SHEET 1 [IF 2 lMINIATURESPINDIQEIPOTENTIOME'I'ERS nn METHOD ron PRODUCING sucrrrorrsnrrowrsrans Miniature spindle potentiometers having, for example, aprofile width of only mm. (millimeter) should have simple componentswhich may be assembled on a mass production basis with a "minimum ofsimple steps into completed potentiometers.

The spindle with its threaded nut constitute the most essentialmechanical components of thepotentiometerj} and they. are responsiblefor'its trouble-free operation with a minimum wear during a'long life.Accordingly, preferential efforts have been devoted in the pastto assuresimple threaded engagement of the spindle with the nut and to theirassembly with the other components within the potentiometer housing on amass production basis.

Such miniature potentiometers must be able to solve two problems:

a. The positioning of a plurality of potentiometers adjacent andparallel to and witha minimum spacing from each other and free fromextraneous disturbances; and

b. The rapid assembly of their components with a minimum of steps in thehousings.

Object (a) is achievedby providing simple potentiometer components whichmay be confined within a small profile of narrow width approaching theprofile of the spindle while assuring disturbance-free operation.

Object (b) i ssolved in the first instance, with a slotted nut havingtwo nut sections embodying elastic material which bias their inwardthreads into positive play-free engagement with the spindle threads.Furthermore, the elastic nut material enables the engaged nut andspindle threads to glide across and over each other without damage orsubstantial wear of the nut threads even when the nut must remainstationary in an end position while the spindle rotates at substantialspeed.

The nut has to move a contact spring in sliding contact engagement witha resistance track and a parallel contact track which extend generallytransversely or perpendicularly to the mounting surface of thepotentiometer.

According to the invention, the potentiometer assembly'is greatlysimplified by providing the nut and the contact spring with a protrusionand recess coupling which readily engage with and couple to each other.

In practice, the nut is formed, as by molding, of strong elastic polymermaterial and is provided with at least one coupling protrusion whichenters into a conforming coupling opening or recess within a transversecoupling sheet section of a U-shaped contact spring having two contactarms which slide along and contact the resistance and contact tracks,respectively.

The foregoing and other objects of the invention will be furtherexplained in the following description of examples thereof in connectionwith the annexed drawings wherein:

FIG. 1 is a cross-sectional view of the miniature potentiometer alonglines l-l of FIG. 2;

FIG. 2 is a cross-sectional view along lines 2-2 of FIG. 1; FIG. 2A is across-sectional view along line 2A2A of FIG.

FIG. 3 is a perspective view of the potentiometer nut;

FIG. 4 is an exploded perspective view of the same nut structure and ofthe sliding contact spring moved thereby;

FIG. 5 is a perspective view of the housing base wall of thepotentiometer with the parallel resistance and contact tracks carriedthereon, and of the U-shaped contact spring held in sliding engagementwith the two tracks;

FIGS. 6A, 6B, 6C, 6D and 6D-l, 6E, 6F and 6G are schematic view ofsuccessive stages or steps of assembling the components of thepotentiometer into completed units.

FIGS. 1 and 2 show an example of a miniature spindle potentiometerexemplifying the invention with some of its components or parts beingshown in FIGS 2A and 3 to 5. The potentiometer has a mounting surfacewith which it is affixed, for example, to the flat surface of a printedcircuit device (not shown) indicated by dash-dot lines 20-A. The

2, potentiometer comprises an elongated spindle 1 having exteriorthreads 1-2 and extendinggenerally. parallel to mounting surface 20. Thespindle l is rotated about its axis and has exteriorthreadsl-3-engaginginward threads l-3of nut 2 for movingthe nut2between'opposite end positions along the spindle l FIG. 1).

The nut 2has aslot or slots 3 which separates it into two nut sectionsor cheeks 5 having the inward threads 2-3 which maintain play-freeengagement with the spindle threads l-3. The nut or nut structure 2 isformed, as by molding, of'elastic insulating material which causeselastic biasing. of the two nut sections 5 into the required play-freeand positive threaded engagement with the spindle 1.. Furthermore,theelastic nut material causes the engaged nut threads 2-3 and spindlethreads l-3to axially glide over and across each other in the directionof the spindle axis without damage and wear of the nut threads evenduring rotation of the spindle l at substantial speed, for instance,while the nut 2 remains stationary in an end position along spindle 1.When released from the spindle, the thread diameter of the nut 2 or nutcheeks Sis smaller than the thread diameter of the spindle 1'. Suchelastically biased nut sections 5 enable play-free threaded engagementof the spindle l with the nut 2, by inserting or pushing the spindle lin its axial direction between the inwardly biased nut sections 5without damage or wear of the nut threads 5-3.

Within the space of the lateral width or diameter of spindle l andlaterally adjacent thereto are mounted and aligned an elongatedresistance track 8 and an elongated metallic contact track 9, bothextending parallel to each other and to the spindle 1 and generallyperpendicularly or transversely to the mounting surface 20 of thepotentiometer.

The potentiometer spindle l and all its other components are confinedwithin a space of small transverse profile of narrow width approachingthe small profile and width of spindle 1.

All potentiometer components are enclosed in an elongated narrow housing10 having a transverse profile and width approaching the profile andwidth of the spindle l. The housing The housing 10 has sidewalls 10-1which are parallel and transverse to walls 10-2, 10-3 which aretransverse to the spindle l. The housing 10 is shown with an open bottomside which is enclosed by a base wall 10-6 having a border facing theborder of the open housing sidewalls 10-2 and transverse wall 10-3.After assembling the potentiometer components within the housing 10, itsborder is united or affixed to the facing border of base wall 10-6 toprovide a junction which suppresses entry of dust and other contaminantsinto its interior. Such junction between the border of housing 10 andits base wall 10-6 may be secured as by supersonic vibration for weldingwithin other known procedures.

Housing base wall 10-6 has the exterior mounting surface 20 and carriesa transverse interior support wall 10-8. Interior support wall 10-8carries the elongated resistance track 8 and metallic contact track 9parallel to each other and transversely to mounting surface 20.Transverse support wall 10-8 is formed of high-quality insulatingmaterial, for example, of substantially pure aluminum oxide having goodheat conductivity and good heat distribution characteristics. Base wall10-6 has a major raised interior wall layer extending into the housinginterior. Transverse support Wall 10-8 has opposite end surfaces 10-9which are aligned with the longitudinal end edges of the most interiorsurfaces of base wall 10-8 for aligning the operative position oftransverse support wall 10-8 with base wall 10-6 and all the componentsof the potentiometer held assembled thereon. The resistance track 8 hastwo opposite metallic terminal end surfaces 8-2 held aligned ontransverse support and base walls 10-8 and 10-6 (FIG. 5).

The nut structure 2 is coupled or connected to and aligned with metalliccontact spring 7 and imparts thereto sliding contact motion along theresistance and contact tracks 8, 9 between their opposite end positionsalong spindle 1..Contact spring 7 (FIGS. 1, 2, 4 and 5) is formed ofU-shaped sheet structure of spring sheet metal and has two oppositecontact arms 7-2 extending from intermediate flat junction section 7-4.The opposite contact arms 7-2 of contact spring 7 are biased intosliding contact engagement with resistance track 8 and contact track 9while being moved by nut 2 between opposite end positions alongspindle 1. In accordance with the invention, the assembly and couplingbetween nut 2 and contact spring 7 is simplified by providing theinsulating nut with one or more coupling projections 6 which enter andfit into recesses or openings 7-6 of junction section 7-4 of U-shapedspring structure 7.

Base wall -6 has embedded therein, as by molding, oppositely biasedportions of elongated connector strips 33, 34, of elastic andelectrically conducting material, such as spring sheet metal. Eachconnector strip 33, 34 has an outward terminal extension for connectionto associated operating circuits. The major inward length of connectorstrips 33 are biased into contact engagement with terminal ends 8-2 ofresistance track 8, and corresponding inward opposite connector strip 34is biased in opposite direction into contact engagement with contacttrack 9. These two oppositely biased connector strips 33, 34 are ofsufficient strength and stiffness to maintain between them transversesupport wall 10-8 with its resistance and contact tracks 8 and 9 alignedin the required operative position on base wall 10-6. The arcuatelyshaped contact ends of contact arms 7-2 will ride over and make contactwith connector strip 34 and therethrough with contact track 9.

One end of the spindle 1 is provided with a spindle head 12 having aslot 13 engageable by a rotating drive element tool such as orresembling a screwdriver, for rotating the spindle 1 around its axis.The transverse housing walls 10-2, 10-3 have recesses or openings forrotatably seating cylindrical end regions of spindle 1. Transversehousing wall 10-3 has a housing extension 11 surrounding the spindlehead 12 for suppressing lateral escape of the rotary tool fromengagement with the spindle head 12 while rotating the spindle 1. Theinward surfaces of the housing extension 11 are purposely roughened sothat they form, with the spindle head 12 and adjoining spindle portion,a labyrinthine packing which suppresses entrance of dust and othercontaminants into housing 10.

In the form seen in FIGS. 1, 2 and 3, the left end of spindle 1 near itshead 12 may have a bearing recess holding therein, for resistance, anannular row of known spherical bearing balls on which the surroundedunthreaded cylindrical spindle portion rotates. The left transversehousing wall 10-3 has a cylindrical opening through which the spindle 1is inserted into the interior housing position seen in FIGS. 1 and 2, sothat its smooth, cylindrical spindle portion to the left of the bearingballs fits within the cylindrical opening of this transverse wall 10-3.The spindle head 12 is separated from the adjoining unthreadedcylindrical spindle portion by a retainer slit which is engaged by theslotted upper end of a retainer spring strip 19 (FIG. 6) which isinserted therein in an upward direction through a slit in the exteriorhousing extension 11 for locking the spindle 1 in its operative position(FIGS. 1, 6F).

The nut 2 is so designed in relation to the contact spring 7 and theadjoining components including the housing 10 as to force the nut 2 tomove longitudinally parallel to the axis of spindle 1 and prevent thenut 2 from being rotated by rotation of spindle 1. Such longitudinalmovement of the nut 2 is secured by making its exterior surfaces in theshape of a rectangular parallel piped or of a cube stretched to have thelonger rectangular exterior wall surfaces in the directions parallel tothe spindle axis. Furthermore, the transverse junction section 7-4 ofthe U-shaped contact spring 7 is flat and of rectangular shape and fitswithin a corresponding rectangularly shaped flat recess 2-5 of nut 2(FIGS. 2 to 5). The U- shaped contact spring 7 is coupled by separatedrecesses in openings 7-6 of its flat junction section 7-4 tocorresponding coupling pin projections 6 of nut 2, thereby preventingrotation of nut 2 and forcing it to move longitudinally parallel to thespindle 1. The most exterior surfaces of nut 2 are flat and they arerectangularly aligned relative to each other. These rectangularlyinclined most exterior surfaces of nut 2 face and are guided by interiorsurfaces of the facing walls of housing 10 and the upper surface ofinterior support wall 10-8 which prevent rotation of nut 2 and cause itto move longitudinally along spindle l by rotation thereof.

Without thereby limiting the scope of the invention, but in order toenable ready practice thereof, there are given below characteristic dataof strong elastic materials suitable for making the slotted nut 2 usedin the potentiometers of the invention. As examples, they compriseacetal homopolymers (DEL- RIN), acetal copolymers (CELCON) andlong-chain amide polymers, known as nylons, such as described in MODERNPLASTICS ENCYCLOPEDIA, 1967, published by McGraw Hill Publications,pages to 144, 204 to 210 and Ill and the references listed therein. Thispublication also gives mechanicalcharacteristics of these materials inthe Charts on pages 39 to 56, including their tensile strength, tensilemodulus, compressive strength, flexural strength, impact strength,flexural modulus and compressive modulus. The characteristics of acetalpolymers (DELRIN) are given in the pages inserted after page 156 by DuPont de Nemours & Co., page 6 of the insert. Also, other knownmechanically strong and elastic polymers, for example, polycarbonates,polyesters. Also, such polymers which are combined with fillers oradditions, such as glass fibers, or fluorocarbon polymers, such aspolytetrafluoroethylene, for example, which secure very materialdecrease of the frictional coefficient of the combined elastic polymermaterials. The transparent housing may be made with known acrylic resinsand modified acrylic polymers, such as described in the samepublication, pages to 119 and the Chart on page 41.

The present invention also comprises novel methods of producing, inaccordance with the invention, miniature spindle potentiometers of theinvention on a rapid mass production basis. FIGS. 6A to 60 showschematically examples of a succession of stages, designated stages A toG, respectively, used for such rapid production of potentiometers of theinvention.

STAGE A (FIGS. 6A; 6A-1 and FIGS. 1 to 5) With known fabricationmethods, there is produced the housing base wall 10-6, such as seen inFIGS. 6A, 6A-1, 1, 2 and 5, of plastic or polymer material, with its twosets of oppositely biased connector bars 33, 34 of elastic sheet springmetal, for instance, extending therefrom and partially embedded therein.The upward main regions of connector bars 33, 34 seen in FIGS. 6A, 6A-1,l, 2 and 3are elastically biased to engage and make electric contactwith terminal regions 8-2 of resistance track 8 and contact track 9,respectively, carried by transverse support wall 10-8.

STAGE B (FIGS. 68 and 6B-1) The transverse insulating support wall 108with the resistance track 8 and contact track 9 held affixed to itsopposite major surfaces is inserted or forced into its operative alignedposition (seen in FIGS. 1, 2 and 5) between the upper elastic sectionsof the two sets of metallic connector bars 33 and 34 which are biasedtoward support wall 10-8 and to establish conductive connections withterminal surfaces 8-2 of resistance track 8 and with contact track 9,respectively. The downward surface of transverse support wall is nowseated on and aligned with the interior surface of housing base wall 10-6 and forms therewith a unitary self-supporting structure with thecomponents held properly aligned thereon.

STAGE C (FIG. 6C)

The U-shaped contact spring 7 is seated as a rider astride over and onthe transverse support wall -8 so that contactspring arms 7-2 (FIGS. 4and 5) engage and make contact with the opposite major outer conductingsurfaces of the resistance track 8 and of the contact track 9 heldexposed thereon. Thereupon the nut 2 is seated against upward surface ofintermediate junction section 7-2 of U-shaped contact spring 7 with thedownward nut coupling pins 6 of nut 2 entering with good coupling fitinto openings 14 of contact spring section 7-4, as explained above inconnection with FIGS. 1 to 5 and FIG. 6C.

STAGE D (FIGS. 6D, 6D-1 and FIGS. 1, 2, 5)

The major upper part of housing 10-as seen in FIGS. 1 and 2-is seatedover housing base wall 10-6 and over all the potentiometer componentsassembled thereon (FIGS. 68 and 6C, and l, 2, 5). The downward border ofthe upper major part of housing 10 is now in contact with the facingborder of base wall 10-6 so that they may be later united to each otherinto an integral housing enclosure.

STAGE 6E (FIG. 6E and FIGS. 1 to 5) The elongated spindle l is inserted(through passage of left transverse housing wall 10-3, as seen inFIG. 1) into the interior of the housing 10 in the direction of thespindle axis. Such insertion causes the teeth 1-3 of spindle l to glideover and across the nut threads 2-3 and between the inwardly biased nutsections 5 and assume the inward operative position of the spindle 1,such as described above in connection with FIGS. 1 to 5.

STAGE F (FIGS. 6F, 1 and 2A) The upper locking fingers of flat lockingspring strip 19 is now inserted through locking slit of housingextension 11 into locking engagement with locking groove of spindle 1(FIG. 2A), with the downward region of locking spring strip 19 flexedoutwardly, as seen in FIG. 6F. Upon releasing the flexed downward end oflocking spring strip 19, it returns to its normal flat shape seen inFIG. 1, wherein it is retained along the exterior of transverse housingwall 10-3 and maintains the spindle 1 locked in the desired finaloperative position within housing 10.

STAGE 6G (FIGS. 6G and 1) With all potentiometer components now fullyassembled in operative positions within housing 10, the potentiometer issubjected to testing and approval. Upon approval, the downward border ofupper housing parallelepiped 10 (as seen in FIG. 1) is joined, as bysupersonic vibration welding, to facing border of base wall 10-6 to formtherewith a solid junction and integral housing enclosure whichsuppresses entry of dust, liquids and other contaminants into thehousing interior. This completes the production of the miniature spindlepotentiometer in accordance with the invention.

SUMMARY Summarizing, the rapid and simplified production of miniaturespindle potentiometers in accordance with the invention is made possibleby novel, multisectional nut 2 of strong, elastically deformable andwear-resistant insulating plastic or polymer material. Suchmultisectional nut 2 of strong, elastically deformable material, whichnormally maintains substantially play-free engagement of it nut threadteeth 2-3 with the spindle thread teeth l-3, departs from the longaccepted practice in the construction of such or analogous spindlepotentiometers. The strong, wear-resistant and elastically deformableinsulating material of the multisectional nut 2, causes the teeth of itsnut threads 2-3 to glide axially across and over the teeth of thespindle threads l-3 in a direction parallel to the spindle axis 1without damage or substantial wear of the nut threads 2-3 during thelong operating life of the potentiometer. As a result, the nut threads2-3 will glide without damage and substantial wear over and across thespindle threads l-3 in a direction parallel to the spindle axis 1 whenthe nut 2 remains stationary in an end position while the spindle 1continues to rotate at substantial speed. Making transparent at leastparts of housing 10 adjoining the spindle (and its nut 2) enables visualchecking of the momentary potentiometer setting during a long operatinglife.

The examples of the best mode for carrying out the invention describedabove will suggest various modifications within the scope of theaccompanying claims.

We claim:

I. A narrow elongated spindle potentiometer having a mounting surfaceaffixable to an electrical device,

an elongated resistance track extending generally transversely to saidmounting surface,

an elongated spindle having exterior threads generally parallel to saidtrack,

a nut structure having two nut sections separated by a slot with eachnut section having inward threads engaging said exterior spindle threadsand moved by rotation of said spindle between spaced end stations alongsaid spindle,

a contact structure having contact elements slidably engaging saidresistance track and connected to and moved by said nut structure alongsaid track,

said nut structure containing insulating elements and also elastic nutelements elastically biasing said inward nut threads into engagementwith said spindle threads;

said elastic elements biasing said inward nut threads into engagementwith said exterior spindle threads and causing said spindle threads andsaid nut threads to glide over each other under relative axial movementbetween said nut structure and said spindle;

said nut structure having the property of maintaining the shape of saidinward nut threads after many repeated axial gliding movements of saidinward nut threads and said spindle threads over each other;

said spindle and said resistance track extending adjacent each other atdifferent spacings from said mounting surface and being confined withina narrow profile approaching the width of said spindle with said movablenut structure seated thereon;

an elongated housing enclosing said spindle with said nut structure andsaid resistance track and having side walls extending along their saidnarrow profile;

said housing having a transverse wall with a passage through which saidspindle is inserted into the interior of said housing and axially intoengagement with the inward threads of said nut structure;

said spindle having a spindle end region extending through saidtransverse wall passage to the exterior of said housing, said transversehousing wall having a housing extension surrounding the spindle endregion and constituting with said spindle end region a labyrinthinepacking suppressing entry of contaminants into the housing interior.

2. A spindle potentiometer as claimed in claim I,

said contact structure comprising a U-shapcd sheet structure ofelectrically conducting spring material,

said nut structure having a coupling projection extending toward saidcontact structure,

said contact sheet structure having a coupling sheet section with acoupling recess fitting in coupling engagement with said couplingprojection and causing said contact structure to move with said nutstructure along said spindle.

3. A spindle potentiometer as claimed in claim 1,

said contact structure being a U-shaped sheet of spring material havingcontact elements biased into sliding contact engagement with saidresistance track.

4. A spindle potentiometer as claimed in claim 1,

said potentiometer also comprising an elongated contact track extendinggenerally parallel to said resistance track and extending within saidhousing and at a spacing corresponding to the spacing of said resistancetrack from said mounting sur face.

5. The method of producing a spindle potentiometer having an elongatedthreaded spindle along the interior of one wall of an elongated housinghaving a profile of minimum area and of a width approaching the width ofsaid spindle, and comprising further ii. a nut of strong elastic polymermaterial having two nut sections separated by a slot and elasticallybiased into threaded engagement with and movement along said spindle inresponse to spindle rotation,

iii. an elongated resistance track and an elongated electricallyconducting contact track extending adjacent and parallel to each otherand to said spindle and transversely to said one wall within saidhousing, and

iv. a U-shaped contact spring moved by said nut and formed of elastic,electrically conducting sheet material having opposite contact armsbiased into sliding engagement with said resistance and contact tracks;

said method comprising a. forming said one wall with said resistancetrack and said contact track extending transversely to and along theinterior of said one wall,

b. thereafter seating said contact spring with said opposite contactarms astride of said two tracks and in engagement with said two tracks,and with said nut seated and coupled to an intermediate section of saidcontact spring,

c. thereafter positioning the remainder of said housing over theinterior of said one wall and around said above specified elements (ii),(iii) and (iv) assembled along said one wall, and

d. thereafter pushing said elongated spindle into the interior of saidhousing, and into threaded engagement with and between said two nutsections while held along said two tracks, and

e. thereafter bonding the borders of said one wall and said remainder ofsaid housing to each other to close said housing along said borders.

6. The method of producing a spindle potentiometer having i. anelongated threaded spindle along the interior of one wall of anelongated housing having a profile of minimum MIMI area and of a widthapproaching the width of said spindle,

and comprising further ii. a nut of strong elastic polymer materialhaving two nut sections separated by a slot and elastically biased intothreaded engagement with and movement along said spindle in response tospindle rotation,

iii. an elongated resistance track and an elongated electricallyconducting contact track held adjacent and parallel to each other and tosaid spindle and transversely to said one wall within said housing, and

iv. a U-shaped contact spring moved by said nut and formed of elastic,electrically conducting sheet material having opposite contact armsbiased into sliding engagement with said resistance and contact tracks;

said method comprising a. producing said one wall of insulating materialwith at least two opposite sets of elongated, strong and elasticconnectors extending from and transversely to said one wall,

b. thereafter inserting said parallel resistance and contact tracksbetween and into engagement with said opposite sets of connectors,

c. thereafter seating said contact spring with said opposite contactarms astride and over and in engagement with said resistance and contacttracks and coupling said nut to said contact spring, and

d. thereafter positioning the remainder of said housing over theinterior of said one wall around and over said 7 above specifiedelements (i), (ii), Siii) and (iv), e. and thereafter pushing said spinde through a housing wall into the operative position in the interior ofsaid housing and into threaded engagement with and between said nutsections. 7. The method of producing a potentiometer as claimed in claim6,

said method comprising, after step (d), the further step of d-l. testingthe operation of the potentiometer components (i), (ii), (iii) and (iv)assembled in said housing and, after step (e), the further step of f.thereafter bonding the borders of said one wall and of said remainder ofsaid housing into a joint suppressing entry of dust into the interior ofsaid housing.

1. A narrow elongated spindle potentiometer having a mounting surfaceaffixable to an electrical device, an elongated resistance trackextending generally transversely to said mounting surface, an elongatedspindle having exterior threads and extending generally parallel to saidtrack, a nut structure having two nut sections separated by a slot witheach nut section having inward threads engaging said exterior spindlethreads and moved by rotation of said spindle between spaced endstations along said spindle, a contact structure having contact elementsslidably engaging said resistance track and connected to and moved bysaid nut structure along said track, said nut structure containinginsulating elements and also elastic nut elements elastically biasingsaid inward nut threads into engagement with said spindle threads; saidelastic elements biasing said inward nut threads into engagement withsaid exterior spindle threads and causing said spindle threads and saidnut threads to glide over each other under relative axial movementbetween said nut structure and said spindle; said nut structure havingthe property of maintaining the shape of said inward nut threads aftermany repeated axial gliding movements of said inward nut threads andsaid spindle threads over each other; said spindle and said resistancetrack extending adjacent each other at different spacings from saidmounting surface and being confined within a narrow profile approachingthe width of said spindle with said movable nut structure seatedthereon; an elongated housing enclosing said spindle with said nutstructure and said resistance track and having side walls extendingalong their said narrow profile; said housing having a transverse wallwith a passage through which said spindle is inserted into the interiorof said housing and axially into engagement with the inward threads ofsaid nut structure; said spindle having a spindle end region extendingthrough said transverse wall passage to the exterior of said housing,said transverse housing wall having a housing extension surrounding thespindle end region and constituting with said spindle end region alabyrinthine packing suppressing entry of contaminants into the housinginterior.
 2. A spindle potentiometer as claimed in claim 1, said contactstructure comprising a U-shaped sheet structure of electricallyconducting spring material, said nut structure having a couplingprojection extending toward said contact structure, said contact sheetstructure having a coupling sheet section with a coupling recess fittingin coupling engagement with said coupling projection and causing saidcontact structure to move with said nut structure along said spindle. 3.A spindle potentiometer as claimed in claim 1, said contact structurebeing a U-shaped sheet of spring material having contact elements biasedinto sliding contact engagement with said resistance track.
 4. A spindlepotentiometer as claimed in claim 1, said potentiometer also comprisingan elongated contact track extending generally parallel to saidresistance track within said housing and at a spacing corresponding tothe spacing of said resistance track from said mounting surface.
 5. Themethod of producing a spindle potentiometer having i. an elongatedthreaded spindle along the interior of one wall of an elongated housinghaving a profile of minimum area and of a width approaching the width ofsaid spindle, and comprising further ii. a nut of strong elastic polymermaterial having two nut sections separated by a slot and elasticallybiased into threaded engagement with and movement along said spindle inresponse to spindle rotation, iii. an elongated resistance track and anelongated electrically conducting contacT track extending adjacent andparallel to each other and to said spindle and transversely to said onewall within said housing, and iv. a U-shaped contact spring moved bysaid nut and formed of elastic, electrically conducting sheet materialhaving opposite contact arms biased into sliding engagement with saidresistance and contact tracks; said method comprising a. forming saidone wall with said resistance track and said contact track extendingtransversely to and along the interior of said one wall, b. thereafterseating said contact spring with said opposite contact arms astride ofsaid two tracks and in engagement with said two tracks, and with saidnut seated and coupled to an intermediate section of said contactspring, c. thereafter positioning the remainder of said housing over theinterior of said one wall and around said above specified elements (ii),(iii) and (iv) assembled along said one wall, and d. thereafter pushingsaid elongated spindle into the interior of said housing, and intothreaded engagement with and between said two nut sections while heldalong said two tracks, and e. thereafter bonding the borders of said onewall and said remainder of said housing to each other to close saidhousing along said borders.
 6. The method of producing a spindlepotentiometer having i. an elongated threaded spindle along the interiorof one wall of an elongated housing having a profile of minimum area andof a width approaching the width of said spindle, and comprising furtherii. a nut of strong elastic polymer material having two nut sectionsseparated by a slot and elastically biased into threaded engagement withand movement along said spindle in response to spindle rotation, iii. anelongated resistance track and an elongated electrically conductingcontact track held adjacent and parallel to each other and to saidspindle and transversely to said one wall within said housing, and iv. aU-shaped contact spring moved by said nut and formed of elastic,electrically conducting sheet material having opposite contact armsbiased into sliding engagement with said resistance and contact tracks;said method comprising a. producing said one wall of insulating materialwith at least two opposite sets of elongated, strong and elasticconnectors extending from and transversely to said one wall, b.thereafter inserting said parallel resistance and contact tracks betweenand into engagement with said opposite sets of connectors, c. thereafterseating said contact spring with said opposite contact arms astride andover and in engagement with said resistance and contact tracks andcoupling said nut to said contact spring, and d. thereafter positioningthe remainder of said housing over the interior of said one wall aroundand over said above specified elements (i), (ii), (iii) and (iv), e. andthereafter pushing said spindle through a housing wall into theoperative position in the interior of said housing and into threadedengagement with and between said nut sections.
 7. The method ofproducing a potentiometer as claimed in claim 6, said method comprising,after step (d), the further step of d-1. testing the operation of thepotentiometer components (i), (ii), (iii) and (iv) assembled in saidhousing and, after step (e), the further step of f. thereafter bondingthe borders of said one wall and of said remainder of said housing intoa joint suppressing entry of dust into the interior of said housing.